Answer:
Fourth option
Explanation:
An m×n matrix is a matrix with m rows (horizontal lines) and n columns (vertical lines).
By definition, the multiplication of two matrices 
 ×
×
 and
 and 
 ×
×
 can be done only if:
 can be done only if:

In the first option:

In the second option

In the third option

In the fourth option

 Multiplication can be done
 Multiplication can be done